检查的属性get_queried_object().

示例代码：

<?php # -*- coding: utf-8 -*-
/**
 * Plugin Name: Current Term Widget
 */

add_action( \'widgets_init\', array ( \'Current_Term_Widget\', \'register\' ) );

class Current_Term_Widget extends WP_Widget
{
    public function __construct()
    {
        parent::__construct( \'current_term\', \'Current Term\' );
    }
    public function widget( $args, $instance )
    {
        if ( isset ( get_queried_object()->taxonomy )
            && isset( get_queried_object()->name )
        )
        {
            return print $args[\'before_widget\']
                . \'<b style="padding:10px;border:3px solid red">\'
                . get_queried_object()->name
                . \'</b>\'
                . $args[\'after_widget\'];
        }
    }
    public static function register()
    {
        register_widget( __CLASS__ );
    }
}

将小部件输出限制为分类比较get_queried_object()->taxonomy 使用您注册的分类名称。